Nanotechnology and quantum information technology are emerging branches of science that involve the design of extremely small electronic and optical circuits that are built at the molecular level. Traditional opto-electronic circuits are fabricated using semiconductor wafers to form chips. Circuits are etched into the semiconductor wafers or chips. The etching process removes material from certain regions or layers of the chips. In contrast, nanotechnology generally deals with devices built upward by adding material, often a single atom at a time. This technique results in a device where every particle could have a purpose. Thus, extremely small devices, much smaller than devices formed by etching, are possible. For example, a logic gate could be constructed from only a few atoms. An electrical conductor can be built from a “nanowire” that is a single atom thick. A bit of data could be represented by the presence or absence of a single proton.
Quantum information technology provides a new avenue for creating smaller and potentially more powerful computers. Scientific theories such as quantum superposition and quantum entanglement are now being used to explore the possibility of creating smaller, more powerful computing devices. The development in this field has led to the use of light particles, or photons, to convey information. Light can be polarized into various states (e.g., horizontally polarized, vertically polarized) and can also exist in various momentum and frequency states. Exploiting these properties allows a single photon to represent a single quantum bit of information.